Electron spin resonance spectroscopy for evaluation of early oxidative events in semisolid palm oil

Abstract

Electron spin resonance (ESR) spectroscopy was applied to study early oxidative events in semisolid palm oil in bulk. Oil was stored at mildly accelerated conditions of 508C for 7 days and the free radical formation was followed with the addition of spin trap N-tert-butyl-a-phenyl-nitrone. Dissolution of the oil samples in isooctane prior to ESR measurements stabilized the ESR signal allowing the changes in relative free radical concentrations during oil storage to be monitored. Formation of lipid hydroperoxides as primary lipid oxidation products was found to correlate with the tendency for the formation of free radicals in the oil during the storage and accordingly, ESR spectroscopy may be used to detect the early events in lipid oxidation in palm oil. However, the interference of added rosemary extract (RE) in ESR analyses was seen as an increased ESR signal while the efficiency of RE as antioxidant in palm oil was confirmed by isothermal DSC.Practical applications: ESR spectroscopy may be used to evaluate early events of oxidation in semisolid oils such as palm fat, which is widely used in food industry.

EPR Spin-Trapping Study of Free Radical Intermediates in Polyalphaolefin Base Oil Autoxidation

“…On the other hand, EPR spin-trapping technique allows studying hydrocarbon degradation on a more fundamental level, provided the free radical mechanism of autoxidation; it allows studying precursors of later stage oxidation products. To our knowledge, previous EPR spin-trapping studies of liquid-phase autoxidation were done only on oxidation-prone edible oils [5][6][7][8][9][10], without focusing specifically on the chemistry of hydroperoxides. Spin-trapping is a technique used to study free radicals by stabilizing them through the reaction with external probes called spin-traps.…”

Oxidation Processes in Sicilian Olive Oils Investigated by a Combination of Optical and EPR Spectroscopy

“…To evaluate different radical formation in olive oil samples, an EPR study has been made as a function of incubation time in the early stages of the oxidation process (up to 6 h). In the last decade the application of EPR spectroscopy to test the antioxidant capacity in edible olive oil was reported as a highly sensitive and reliable technique (Ottaviani and others 2001; Papadimitriou and others 2006; Koprivnjak and others 2008; Raitio and others 2011). Usually, the concentration of free radicals produced during the oxidation process is not high enough to be directly detected by standard assays.…”

Evaluation of the Oxidation Degradation Process of Biodiesel via 1H NMR Spectroscopy

“…These natural antioxidants have the advantage of being inexpensive and non-toxic. 18 In the literature there are different papers reporting the antioxidant properties and efficiency of different plants as rosemary, [19][20][21] blackberry, 5,22 senna leaves, 23 hibiscus, 23,24 oregano, 25 basil, 25 curcumin, 26 β-carotene, [26][27][28] etc. 1 H NMR (proton nuclear magnetic resonance) spectroscopy has been used along with standard analysis to analyze oils and its compositions regarded to acylglycerols, fatty acid alkyl esters (FAAEs), its byproducts.…”

“…The alcoholic extract of rosemary (Rosmarinus officinalis) was produced using 10 g of dry rosemary leaves, according to the methodology established by Romagnoli et al 23 The use of this extract was determined based on previous results and literature. 19,20,35 Ten grams of rosemary leaves were added to 250 mL of ethanol (99.5%, Anidrol PA, Diadema, Brazil) and mixed with a glass stick. The mixture was kept for 48 h and the extracts were filtered.…”